The present invention generally relates to apparatus for dispensing micro liter amounts of medicament and is more particularly directed to apparatus for instilling a medicament into an eye.
A great number of devices have been developed for instilling medicament to an eye. Well known eye drop containers conventionally include a squeezable container and a nozzle for releasing drops of medicament into the eye by compression of the container. Obviously, this apparatus affords no practical method of dispensing a measured dose of medicament inasmuch as the liquid dispensed from the nozzle is dependent upon the amount of compression of the container. Thus, there is no way of accurately controlling the volume of each dose of medicament released into the eye and, further, the smallest drop obtainable is the result of the combined effective gravity and surface tension.
When preservative-free medicaments are utilized, simple eye drop dispensers are not practical because there are no means for preventing the tip from being contaminated due to its exposure to air. Such tip contamination ultimately spreads to the medicament in the container.
In an attempt to overcome these problems, apparatus has been developed for applying a medicament to an eye which includes a nozzle having a seam which is normally in a closed position for preventing the passage of medicament through the nozzle, and which opens in response to a flow of medicament of sufficient pressure to enable opening of the seam in order to permit the passage of medicament through the nozzle for release into the eye, see U.S. Pat. No. 5,685,869.
While this nozzle is suitable, there is difficulty in coupling the nozzle with a suitable reservoir of medicament in order to create a working, producible device for multiple dose delivery of a preservative-free product of sufficient dose accuracy for consumer benefit and regulatory body registration over an extended period of time of up to six months or more.
Operation of prior art devices such as set forth in the hereinabove referenced U.S. patent typically causes a small negative pressure or vacuum within the medicament container during operation. When a collapsible container is utilized to accommodate shrinking of volume of the medicament reservoir, the materials of construction do not satisfactorily inhibit the permeating of air through the container walls to provide a desired long term use in storage of the device without compromise of the stored medicament.
U.S. patent application Ser. No. 09/435,703 filed Nov. 8, 1999 entitled MULTIPLE PRECISION DOSE PRESERVATIVE FREE MEDICATION DELIVERY SYSTEM provides a nozzle and medicament reservoir combination which enables multiple dose delivery of a preservative-free product with accurate dose dispensing over extended periods of time.
The delivery system disclosed in the hereinabove referenced Ser. No. 09/435,703 required axial movement in order to compress a spring for operation thereof. No mechanical advantage is provided and the force required may be objectionably excessive which could cause user dissatisfaction with the delivery system.
The present invention provides for apparatus enabling the axial compression of a spring by rotation of a collar, handle, knob or ring. Further, the apparatus in accordance with the present invention provides a mechanical advantage though the use of an incline in order to reduce the force required of the patient for utilizing the system.
Apparatus in accordance with the present invention for operating an eye drop dispenser, including a chamber for containing a medicament, a nozzle for instilling a dose of medicament into an eye and a spring driven actuator for metering doses of medicament from the chamber to the nozzle, generally includes a housing for removably receiving the chamber and a collar disposed for rotation about the housing for compressing the actuator spring by twisting said collar about the housing. A trigger disposed in the housing is provided for releasing the compress spring.
More particularly, the collar includes a ring with an internal cam surface and the apparatus further comprising a mandrel for supporting the collar and ring for rotation thereabout. A slider is disposed within the mandrel and includes a traveler for engaging a cam surface through a slot in the mandrel. Rotation of the collar causes longitudinal movement of the traveler and slider for compressing the spring.
In addition, the ring may include an internal gear tooth surface and the mandrel may include a ratchet for engaging the tooth which enables rotation of the collar and ring only in a direction for compressing the spring.
More particularly, the slider includes a hook latch for holding the slider in a position compressing the spring and the trigger includes a push button and a depending member having a strikeplate for engaging a hook latch.
In addition, the trigger may further include a leaf spring for engaging the strikeplate into a position for engaging the hook latch, the switch plate being moved out of engagement with the hook latch upon depression of the push button.
In combination, the present invention provides apparatus for instilling a medicament into an eye which includes a housing having a longitudinal axis and a chamber disposed in the housing for containing a medicament. A nozzle is provided for instilling a dose of medicament into an eye and an actuator for metering doses of medicament from the chamber to the nozzle and forcing the metered doses through the nozzle upon axial displacement of the actuator along the housing longitudinal axis.
A spring is provided for causing the lateral displacement of the actuator upon release of the spring from a compressed state.
A collar, disposed for rotation about the housing longitudinal axis, is provided for compressing the spring by twisting the collar about the housing longitudinal axis and a trigger disposed in the housing is provided for releasing the depressed spring.
In this combination, the collar includes a ring with an internal cam surface and the apparatus further comprises a mandrel for supporting the collar and ring for rotation thereabout along with a slider disposed within the mandrel having a traveler for engaging the cam surface through a slot in the mandrel. Rotation of the collar and ring causes longitudinal movement of the traveler and slider for compressing the spring.
The ring may include an internal tooth surface and the mandrel may include a ratchet for engaging the gear tooth surface for enabling rotation of the collar and ring only in a direction for compressing a spring.
Preferably, the slider includes a hook latch for holding slider in a position compressing a spring and a trigger includes a push botton with a depending member having a strikeplate for engaging the hook latch. Preferably the trigger includes a leaf spring for urging a strikeplate into a position for engaging a hook latch with a strikeplate being moved out of engagement with the hook latch upon depression of the push bottom in order to release the spring.
In addition, the chamber and nozzle and actuator may be removed as a single unit, thus enabling replenishment of medicament.